This invention relates generally to a cell analysis apparatus, and more particularly to a cell analysis apparatus of the type which is suited for analyzing cells in a biological liquid sample, such as blood, after staining the cells.
One known method of classifying and analyzing cells (e.g. blood corpuscles) in a blood sample or counting the cells in terms of particles uses a sheath flow cell. A first publication describing an analysis method of this type is Japanese Patent Publication No. 59-853(B). This publication describes a method in which leukocytes (white corpuscles) are stained with acridine orange, and a sample containing the staining agent and the leukocytes is caused to flow through a sheath flow cell. A laser beam is then applied to the sheath flow cell, and the fluorescence of the leukocytes is detected so as to classify the leukocytes.
A second publication describing the use of a sheath flow cell is Japanese Patent Laid-Open No. 59-228147(A). This second publication describes a blood corpuscle counter in which blood corpuscle-suspended liquid is caused to flow through the sheath flow cell, and a laser beam is applied to the sheath flow cell. The forward-scattering light is then detected so as to find the number of the blood corpuscles and the distribution of the particles.
This second publication describes a pretreatment for diluting the blood sample. More specifically, a predetermined amount of the blood sample, introduced from a sample vessel via a nozzle, is metered by a first flow switch valve, and then is fed to a dilution vessel having on-off valves at its upper and lower portions, where the blood sample is diluted. Thereafter, the diluted sample is metered by a second flow switch valve, and is caused to flow through the sheath flow cell so that the number of the blood corpuscles can be counted.
A third publication describing the use of a sheath flow cell is Japanese Patent Laid-Open No. 2-80937(A). This third publication describes an analysis apparatus in which a number of sample cups are successively located at a sample suction position, and a sample in the sample cup is fed to the sheath flow cell by a pipet nozzle, where scattering light or fluorescence of the leukocyte is detected. The pretreated blood sample is contained in the sample cup, and the blood corpuscle-containing sample in the sample cup is drawn by the pipet nozzle.
In the above Japanese Patent Publication No. 59-853(B), although the conditions of the staining of the leukocytes are described in detail, no consideration is given at all to an apparatus for automating the staining treatment. When measuring the blood corpuscle cells, pretreatments, such as dilution, staining and hemolysis, are needed. Similarly, the above third publication also gives no consideration to the automation of the pretreatments.
In the above Japanese Patent Laid-Open No. 59-228147(A), although the dilution of the blood sample is automated, the number of the component parts is large, so that the flow passage system is long. Therefore, the analysis apparatus is of a large size, and it takes much time to wash the flow passage system. In addition, in this technique, the two flow switch valves provided between the sample vessel and the flow cell have the sole function of metering the sample.